XLSX (Excel)
Also known as: xlsx file, Excel spreadsheet, Microsoft Excel format
XLSX is the default file format for Microsoft Excel spreadsheets since Excel 2007. Like DOCX, it is a ZIP package of XML, so even large data tables stay compact unless they hold embedded charts, images, or heavy formatting.
- Default Excel format since Excel 2007
- A ZIP package of compressed XML per worksheet
- Charts, images, and stray formatting inflate it
What is inside an XLSX
An .xlsx file packages each worksheet, its formulas, and its styles as compressed XML inside a ZIP archive. Plain numeric data compresses extremely well, so spreadsheets with thousands of rows can still be small.
What adds weight is embedded charts, pivot caches, conditional formatting across huge ranges, and pasted images. A bloated file is often carrying a leftover pivot cache or a sheet styled far past the data.
XLSX and storage
Spreadsheets are usually a minor part of device storage, but cloud-synced folders full of them still count against your plan. Saving as .xlsx rather than the old binary .xls generally yields a smaller, more portable file.
For sharing or printing, /tools/excel-to-pdf renders a sheet to a fixed PDF, and /tools/pdf-to-excel pulls tabular data out of a PDF back into a spreadsheet.